1. Field of the Invention
The present invention relates to transportation systems, and more particularly to a device for transporting various roofing materials along the rooftop of a building for installation onto the rooftop.
2. Description of the Prior Art
It is well known that constructing a rooftop requires the placement of several layers of different roofing materials upon the building purlins. These roofing materials consist of one or more layers of insulation material, which are then covered by tile or, on many commercial buildings, sheets of metal roofing. These metal sheets are generally provided in large sections, and are bulky and difficult to manage. The sheets must be lifted onto the rooftop, transported or manually carried across the purlins to their respective destinations, and installed. Furthermore, the tradespersons handling these layers must often work upon the exposed purlins while carrying these materials. Even on non-windy days, this poses significant safety risks to the tradesperson and to those below.
The traditional process for transporting, handling and ultimately installing such materials is time-consuming. Depending upon the material to be installed, this may require the cooperation of several tradespersons to lift and move each sheet. First, several sheets of a particular roofing material are bundled together and hoisted onto the rooftop. Tradespersons on the roof must then unbundle each sheet, carry it across the exposed purlins to its destination, and install it. They must then return to the bundle to repeat the process. This task is further complicated by the fact that the distance from the bundle to the placement location increases as the work progresses, requiring more time and effort to transport each individual sheet to its ultimate destination. The work continues until the final sheet of material is installed at the opposite end of the rooftop.
A variety of devices have been developed to transport these materials upon the rooftops, many of which involve transportation devices movably mounted upon the purlins. For example, U.S. Pat. No. 4,068,446 discloses a movable platform that travels along the purlins by internal means of locomotion. This platform is large enough to support several tradespersons, and allow them to work from atop the platform. A fence surrounds the platform to prevent the tradespersons from falling. Outrigger arms, a winch assembly, and an insulation roller system increase the functionality of this device. Furthermore, the device may travel from the purlin onto a completed roof panel via rails placed onto the panel.
U.S. Pat. No. 6,216,416 discloses a dual sectional working platform, also traveling upon the purlins. One section serves as the materials handling area, where various roofing materials are installed onto the purlins. The other section serves as a support platform for the tradespersons while they install the materials. A series of rollers along one side of the platform allow tradespersons to move roofing materials from one end of the platform to the other. The platform itself is moved via a winch connecting the platform to the far end of the roof; this winch is manually turned to move the platform.
U.S. Pat. No. 5,749,434 discloses a device for transporting roofing materials specifically along pitched rooftops. The device consists of various roller assemblies movably mounted onto the purlins, with pipes connecting the assemblies to form a single platform. The roofing materials are placed onto the platform, and held in place by stop pieces installed at the ends of the platform. This device is then dragged behind the tradespersons as they install the roofing materials.
Unfortunately, none of the above described devices are particularly suited for simple and lightweight travel upon sections of completed rooftops. Most of the above described inventions are designed to travel solely upon the building purlins. Thus, their movements and directions are limited by the particular placement of the purlins, and further limited to those sections of the rooftop where the purlins remain exposed. The '446 invention does provide one particular method claim which allows that invention to move onto a section of completed rooftop. However, any such extended movement is generally impractical given the size and weight of the invention, since prolonged use of the invention in such a manner risks damage to the rooftop from the sheer weight and bulk of the invention.
This reveals another inherent problem with many of the above described inventions, namely that they are generally large and heavy. Most of them contain locomotive means, and various other features that assist in the actual placement and installation of the roofing materials. Those inventions must furthermore be sturdy and large enough to support the weight and movement of several tradespersons upon the devices themselves, in addition to the weight of the roofing materials. Such features are beneficial, but they also increase the size and weight of the inventions. They also increase the costs of purchasing and deploying the devices, as well as maintaining them over time. A final drawback is that those inventions are not readily expandable; they are limited to carrying only certain dimensions of roofing material, and may not be sufficiently large to carry certain other materials.
It is therefore desirable to provide a lightweight and expandable device for use in transporting various roofing materials upon sections of completed roofing, such that they may then be installed onto their proper locations.